Strange Secondary Air Valve

[Novarolla05]

Hello all,

I came across an air valve setup I've never seen before, and can't seem to find anything about. The carb number is 17080212. One of the air valves has a small flap attached to the underside at about a 45* angle. The other flap is normal with no notches or anything. Since its only on one flap, I'm thinking this carb has been reworked (incorrectly?) at some point, but its only for parts so it really doesn't matter (primaries look melted from a fire or something). Has anybody else seen air valves like this before, and are they any better than just a plain air valve?

I'll try to post pics when I get home if none of this makes sense.

Thanks,
Richie

[Ethan1]

 Can you post a photo of what you are describing?

[Novarolla05]

Ok, I finally got around to snapping a pic of the air valve. Here it is:


Richie

[Ethan1]

 I have never seen anything like that. Looks like some sort of "baffle" maybe? I don't know. We will see if someone recognizes it.

[Novarolla05]

FWIW, the part number stamped on it is 58583. The other air valve that was on the carb (the normal one) was 58411.

Richie

[Shark Racer]

I can't help but wonder if it's a "performance mod" meant to even out cylinder distribution.

[Ethan1]

I can't help but wonder if it's a "performance mod" meant to even out cylinder distribution.

 Could be, Steve. Makes sense.

[Novarolla05]

That's kinda what I figured as well. With the air valve open all the way, the extra flap is right in front of the fuel nozzles. I was thinking it might be to help direct the fuel more downward. Since it seems pretty unique/rare, I guess its safe to assume it didn't make much difference in performance.

I wonder if JET Performance or some other company that does rebuilds made their own custom flaps. Still doesn't explain why there was only one like it though.

Richie

[Shark Racer]

A notch in front of the fuel discharge holes will help more than anything, look at Cliff's book or poke around the net for pictures of some of the "High Output" Pontiac Quadrajets and you'll see what the factory offered.

[Novarolla05]

I agree Shark Racer, I've done the notching mod, and it definitely improved the transition to the secondaries when I mash the go pedal. I guess for now this flap will remain a mystery.

Thank you both for all your input!

Richie